非共价键改性可逆共价交联网络的制备及性质研究

发布时间：2018-08-26 17:12

【摘要】：基于可逆交联反应的本征型自修复材料因其能够自发的从分子水平上对材料进行修复,延长材料的使用寿命、拓宽材料的应用范围、降低材料的使用成本而成为研究热点。共价键相对于非共价键而言具有更高的键能,因此,共价交联聚合物相对于非共价交联体系来说具有更好的力学强度,更适合于结构材料的使用。将可逆交联反应引入共价交联聚合物可得到一类新型的具有自修复功能的交联聚合物。但是由于可逆共价键与传统共价键相比较小的键能,使得可逆交联聚合物通常达不到理想的强度。因此,在提高可逆交联聚合物强度的同时不影响其自修复效果是目前尚待解决的一个难题。为提高材料的力学性能,生物体常采用的一种方法为在材料中引入非共价键作为牺牲键,当受外力作用时,非共价键首先发生断裂消耗部分能量而保证了材料不受破坏。采用仿生的方法,在可逆共价交联聚合物中引入非共价键有望进一步提高其力学性能,而非共价键本身具有的可逆特性不会影响其自修复效果。本论文以二硫键及Zn~(2+)-咪唑配位键为基础,设计合成了共价与非共价双交联聚合物网络,以及共价交联及非共价交联互穿网络两种交联聚合物体系来研究非共价键的引入以及非共价交联在可逆共价交联网络中的引入方式对可逆共价交联聚合物的影响,采用核磁共振仪、傅里叶红外光谱仪、热重分析仪、动态机械热分析仪、偏光显微镜、扫描电子显微镜、万能试验机等测试手段对聚合物的结构、热力学性能、表面形态、力学性能及自修复性能等进行了表征和分析,期望为具有良好力学性能和修复效果的交联聚合物的开发提供新的思路。具体研究内容如下:首先采用聚丙二醇二缩水甘油醚(ppgdge)及1-(3-氨基丙基)咪唑(api)以2:1的摩尔比反应得到含咪唑基团及端环氧基的二聚体,随后通过zn~(2+)与咪唑形成配位键非共价交联,再利用4’4-二氨基二苯二硫醚(afd)为固化剂与环氧基团进行开环反应得到双交联网络,同时合成了不含zn~(2+)-咪唑非共价交联的可逆共价交联网络作为对比。利用核磁、红外等手段证明了双交联网络的化学结构。采用tga、dma、万能试验机等研究了双交联网络的热力学和力学性能。实验结果表明非共价键的引入大大提高了聚合物的力学性能,循环拉伸测试说明了力学性能提高的原因在于非共价键对外力作用的能量耗散。利用偏光显微镜及万能试验机测试了双交联网络在断裂后的修复性能。实验结果表明在高温时,由于二硫键及金属配位键均发生交换反应,所以双交联网络及共价交联网络均表现出良好的修复性能。在温度较低时,共价交联网络由于二硫键不能发生交换反应,所以不能进行修复,而双交联网络由于非共价键的交换反应则恢复了部分力学性能,证明了非共价键有利于聚合物材料的自修复。重塑实验则表明了双交联网络及共价交联网络在彻底破坏后均能重复加工,达到降低材料使用成本的目的。其次,为充分发挥可逆共价(rcn)及可逆非共价(rncn)两种交联网络的优势,制备了具有互穿网络结构的聚合物(IPN),研究了RCN及RnCN在互穿网络中所占含量不同对IPN性能的影响。采用SAXS和SEM等表征了IPN的结构,采用TGA、DMA及万能试验机等对其热力学性能和自修复性能等进行了测试。结果表明:IPN的Tg介于RCN和Rn CN之间,说明两者具有良好的相容性;SAXS的测试显示IPN与RCN和RnCN出现同样的规律,表明IPN并未发生微相分离;SEM也表明RCN与RnCN共混后形成了均一体系。循环拉伸试验发现,样品受外力作用时,非共价交联网络首先受到破坏,而保证共价交联网络的完整,达到较好的增韧效果。纯RCN的断裂伸长率为44.1%,随着Rn CN含量的增多,断裂伸长率达200%。修复测试表明RCN修复48h后修复效率仅达80%左右,而IPN在同样条件下修复12h,修复效率即可达90%以上。本章研究表明,将可逆共价及可逆非共价交联网络以互穿网络的形式结合同样可以起到增强力学性能及提高修复效率的目的。
[Abstract]:The intrinsic self-repairing materials based on reversible cross-linking reaction have become a research hotspot because they can repair materials spontaneously at the molecular level, prolong the service life of materials, broaden the application range of materials, and reduce the cost of materials. Compared with non-covalent crosslinking systems, compounds have better mechanical strength and are more suitable for the use of structural materials. A new class of self-repairing crosslinked polymers can be obtained by introducing reversible crosslinking reaction into covalent crosslinking polymers. However, reversible covalent bonds have less bond energy than traditional covalent bonds, which makes reversible crosslinking possible. It is a difficult problem to improve the strength of reversible crosslinked polymers without affecting their self-repairing effect. In order to improve the mechanical properties of materials, a method of introducing non-covalent bonds into materials as sacrificial bonds is often adopted by organisms. The covalent bond breaks first and consumes part of the energy to ensure that the material is not destroyed. The introduction of non-covalent bonds into reversible covalent crosslinked polymers by biomimetic method is expected to further improve their mechanical properties, but the reversibility of the non-covalent bond itself will not affect its self-healing effect. Based on coordination bonds, covalent and non-covalent crosslinked polymer networks and covalent crosslinked and non-covalent crosslinked interpenetrating networks were designed and synthesized to study the effect of the introduction of non-covalent bonds and the introduction of non-covalent crosslinking in reversible covalent crosslinking networks on reversible covalent crosslinked polymers. The structure, thermodynamic properties, surface morphology, mechanical properties and self-repairing properties of the polymer were characterized and analyzed by means of magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, dynamic mechanical thermal analysis, polarizing microscope, scanning electron microscope and universal testing machine. The specific research contents are as follows: firstly, the dimer containing imidazole group and epoxy-terminated group was synthesized by the reaction of polypropylene glycol diglycidyl ether (ppgdge) and 1 - (3-aminopropyl) imidazole (api) at the molar ratio of 2:1, and then non-covalent cross-linking of imidazole with Zn ~ (2 +) was formed. A reversible covalent crosslinking network without Zn ~ (2 +) - imidazole was synthesized by ring-opening reaction of 4'4-diaminodiphenyl disulfide (afd) with epoxy group as curing agent. The chemical structure of the network was proved by means of nuclear magnetic resonance and infrared spectroscopy. The thermodynamics and mechanical properties of the bi-crosslinking network were investigated. The results showed that the introduction of non-covalent bonds greatly improved the mechanical properties of the polymer. The cyclic tensile test showed that the reason for the improvement was the energy dissipation of the non-covalent bonds. The experimental results show that at high temperatures, disulfide bonds and metal coordination bonds exchange reactions, so the double cross-linking network and covalent cross-linking network show good repair performance. At low temperatures, covalent cross-linking network can not be repaired because disulfide bonds can not exchange reactions, but double cross-linking. The network restored some mechanical properties due to the exchange reaction of non-covalent bonds, which proved that non-covalent bonds were conducive to self-repairing of polymer materials. The remodeling experiments showed that both the bi-crosslinking network and the covalent crosslinking network could be reprocessed after being completely destroyed, so as to reduce the cost of material use. Secondly, in order to give full play to the reversible covalent network. Polymers (IPN) with interpenetrating network structure were prepared by using valence (rcn) and reversible non-covalence (rncn) crosslinking networks. The effects of different contents of RCN and RnCN in IPN on the properties of IPN were studied. The structure of IPN was characterized by SAXS and SEM, and its thermodynamic properties and self-repairing properties were characterized by TGA, DMA and universal testing machine. The results show that the Tg of IPN is between RCN and RnCN, indicating that they have good compatibility; SAXS test shows that IPN and RCN and RnCN have the same rule, indicating that IPN does not have microphase separation; SEM also shows that the blend of RCN and RnCN forms a homogeneous system. The breaking elongation of pure RCN was 44.1%. With the increase of Rn CN content, the breaking elongation reached 200%. The repair test showed that the repair efficiency of RCN was only about 80% after 48 hours, while that of IPN was about 12 hours under the same conditions. The research in this chapter shows that the combination of reversible covalent and reversible non-covalent crosslinking networks in the form of IPN can also enhance the mechanical properties and improve the repair efficiency.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB381

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